Phase detectors and frequency detectors are found in numerous applications of all modern technologies. They are widely used in areas of electronics and in different fields of communication, in particular the field of telecommunication.
Basically, a phase detector is an arrangement for measuring a phase difference between two input signals. It is well known in the art to use a start and stop counter which receives two input signals. One input signal starts the counter and the other input signal stops the counter, the counter value being representative of the phase difference between the two input signals.
In many applications there is a general need for measuring phase differences between several input signals. Should a phase detector having only two inputs be used for this purpose, it has to be duplicated several times in order to simultaneously handle a plurality of input signals.
Existing alternative techniques to measure phase differences between several input signals usually involves complicated and extensive circuitry.
In earlier phase detector arrangements supervision and maintenance are provided as additional overlay functions. The supervision is implemented as specially designed functions in separate units. This conventional solution requires a significant amount of additional circuitry.